To provide a wastewater treatment apparatus capable of effectively oxidizing and decomposing a hardly oxidizable substance by catalytic oxidation using ozone to remove the same from water to be treated in which an easily oxidizable substance and the hardly oxidizable substance such as an endocrine disrupter or the like coxist.

In the wastewater treatment apparatus having an ozone oxidation tank and a catalytic oxidation tank respectively provided to the front and rear stages thereof, the exhaust gas discharged from the ozone oxidation tank is blown in the catalytic oxidation tank.